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BCNF Decomposition — Details

Decompose a relation


decompose(R: relation, X: set of columns): (relation, relation)
    C = closure(X)
    S = new relation from columns in C
    T = new relation from columns in (R.columns − (C − X))
    return S, T

(C − X) is the RHS of the FD on which the decomposition is based.
(R.columns − (C − X)) includes the LHS, and excludes the RHS.

Example

Decompose BadAlbum(artist, artist_website, title, year, label, label_website) using {artist}.

C = {artist, artist_website}
new relation S(artist, artist_website)
new relation T(artist, title, year, label, label_website)

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